Heat exchanger configuration for adsorption-based onboard octane on-demand and cetane on-demand

ABSTRACT

A vehicular propulsion system, a vehicular fuel system and a method of operating an internal combustion engine. A separation unit that makes up a part of the fuel system includes one or more adsorbent-based chambers such that the separation unit may selectively receive and separate at least a portion of onboard fuel into octane-enhanced and cetane-enhanced fuel components. A supply tank includes three compartments where the first contains the onboard fuel, the second receives a vaporized adsorbate from the separation unit and condenses at least a part of it into one of an octane-rich fuel component or a cetane-rich fuel component, while the third may either store the condensed and enriched fuel component or help condense more of the vaporized adsorbate. The condensing takes place through heat exchange between the onboard fuel and the vaporized adsorbate that are present within the various compartments of the supply tank. A controller may be used to determine a particular operational condition of the internal combustion engine such that the onboard fuel can be sent to one or more combustion chambers within the internal combustion engine without first passing through the separation unit, or instead to the separation unit in situations where the internal combustion engine may require an octane-rich or cetane-rich mixture.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 15/885,084 filed Jan. 31, 2018, the entiredisclosure of which is hereby incorporated herein by reference.

BACKGROUND

The present disclosure relates generally to a vehicular fuel system forselectively separating an onboard fuel into octane-rich and cetane-richcomponents, and more particularly to such a system that promotes heatbalance as part of such onboard fuel separation in such a way to reducethe size, weight and complexity associated with such fuel separationactivities.

SUMMARY

Within the realm of internal combustion engines (ICEs) used forvehicular propulsion, it is the four-cycle variant (with its intake,compression, combustion and exhaust strokes) that is most commonly inuse, where the combustion is typically achieved through either a sparkignition (SI) or compression ignition (CI) mode of operation. InSI-based modes, a mixture of air and fuel (typically octane-richgasoline) is introduced into a combustion chamber for compression andsubsequent ignition via spark plug. In CI-based engines, fuel (typicallycetane-rich diesel fuel) is introduced into the combustion chamber wherethe air is already present in a highly compressed form such that theelevated temperature within the chamber that accompanies the increasedpressure causes the fuel to auto-ignite. Of the two, the CI mode tendsto operate with greater efficiency, while the SI mode tends to operatewith lower emissions.

Various engine concepts or configurations may mimic the relatively lowemissions of an SI mode of operation while simultaneously satisfying thehigh efficiency operation of a CI mode of operation. Such concepts go byvarious names, and include gasoline direct injection compressionignition (GDCI), homogenous charge compression ignition (HCCI),reactivity controlled compression ignition (RCCI), as well as others. Inone form, a single fuel may be used, while in others, multiple fuels ofdiffering reactivities, usually in the form of selectiveoctane-enrichment or cetane-enrichment, may be introduced. Whileperforming octane on demand (OOD) or cetane on demand (COD) as a way offueling these engines is possible, such activities may be fraught withproblems. For example, having the respective octane-enriched orcetane-enriched portions be in either pre-separated form involves theparallel use of at least two onboard storage tanks and associateddelivery conduit. In addition, the time and complexity associated withvehicle refueling activity in this circumstance renders the possibilityof operator error significant. Likewise, OOD or COD generation once thesingle market fuel is already onboard may require distillation ormembrane-based permeation-evaporation (pervaporation) activities thatare accompanied by significant increases in size, weight and overallcomplexity of the onboard fuel-reforming infrastructure. Thesedifficulties are particularly acute as they relate to achieving a heatbalance associated with the underlying fuel enrichment activities. Assuch, a simplified approach to integrating such infrastructure into anonboard fuel separation system is warranted.

According to one embodiment of the present disclosure, a vehicularpropulsion system is disclosed. The propulsion system includes an ICEwith a combustion chamber, as well as a fuel system for converting anonboard fuel into octane-rich and cetane-rich fuel components. The fuelsystem includes a fuel supply tank (also referred to as an onboard fueltank or main tank) for containing the onboard fuel, a separation unit, aproduct tank and fuel conduit. The separation unit includes one or moreadsorbent-based chambers each to selectively receive and separate atleast a portion of an onboard fuel into an adsorbate and a remainder.The product tank may selectively receive and contain the remainder as acetane-rich fuel component. The fuel supply tank includes first, secondand third compartments such that together they help the fuel supply tankalso act as a compact heat exchanger. The first compartment is used tocontain the onboard fuel. The second compartment is disposed within thefirst compartment and may receive a vaporized form of the adsorbate fromthe separation unit. In this way, at least some of the vaporized form ofthe adsorbate that is present in the second compartment is condensedinto an octane-rich fuel component through the thermal communication andconsequent exchange of heat with the onboard fuel that is present in thefirst compartment. The third compartment is disposed within the secondcompartment and is both fluidly and thermally coupled to the secondcompartment; in this way, at least a portion of any remaining vaporizedform of the adsorbate from the second compartment may be conveyed to thethird compartment for at least one of storage and additional condensinginto more of the octane-rich fuel component. Fuel conduit is used toestablish fluid communication between various components that make upthe fuel system so that at least one of the onboard fuel, theoctane-rich fuel component and the cetane-rich fuel component may beconveyed to the combustion chamber from at least one of the separationunit, fuel supply tank and product tank.

According to another embodiment of the present disclosure, a vehicularfuel system for converting an onboard fuel into octane-rich andcetane-rich components is disclosed. The fuel system includes a fuelsupply tank, conduit, a separation unit and a product tank. The fuelsupply tank includes a first compartment for containing the onboardfuel, a second compartment and a third compartment in a manner similarto that of the previous embodiment where the various compartmentsexhibit one or both of thermal and fluid communication with one anotherin order to promote the formation of the adsorbate into a suitableoctane-rich fuel component or cetane-rich fuel component in such a waythat minimizes or avoids the use of redundant structure.

According to yet another embodiment of the present disclosure, a methodof operating an internal combustion engine is disclosed. The methodincludes configuring a fuel system to have a heat-exchanger-basedonboard fuel supply tank, a separation unit, a separate heat exchanger,a first product tank and a second product tank, as well as fuel conduit.A controller provides directions to at least some of the othercomponents so that the controller can ascertain an operational conditionof the internal combustion engine and then direct the flow of a portionof the onboard fuel to either the combustion chamber of the engine or tothe separation unit depending on the engine operational condition. In afirst ascertained engine condition, the onboard fuel flow does notinteract with the separation unit, instead going to the combustionchamber for immediate use by the engine. In a second ascertained enginecondition, the onboard fuel flow interacts with the separation unit suchthat an adsorbent portion of the onboard fuel collects on a surface ofat least one of a plurality of chambers of the separation unit, while aremainder portion that is not adsorbed is routed to a storage tank. Theheat exchange features of the onboard fuel supply tank include a firstcompartment, second compartment and third compartment in a mannersimilar to that of the previous embodiments such that an adsorbate thathas been vaporized (that is to say, desorbed) by the operation of theseparation unit may be condensed into a usable fuel component.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following detailed description of specific embodiments of thepresent disclosure can be best understood when read in conjunction withthe following drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 shows a vehicle with a partial cutaway view of an engine inaccordance with one or more embodiments shown or described;

FIG. 2 shows a simplified cutaway view of a cylinder of the engine ofFIG. 1 along with a controller in accordance with one or moreembodiments shown or described;

FIG. 3 illustrates a simplified view of an onboard fuel separationsystem in accordance with one or more embodiments shown or described;

FIG. 4 illustrates an adsorption rate of a highly aromatic fuel compoundon a particular adsorbent functional group that may be used in theonboard fuel separation system of FIG. 3; and

FIG. 5 illustrates an exemplary adsorbate flow rate under three separatetime periods in accordance with one or more embodiments shown ordescribed.

DETAILED DESCRIPTION

In the present disclosure, an adsorption-based separation system may beused to split an onboard fuel into OOD or COD streams by takingadvantage of one of two specific mechanisms: (1) employing differingfunctional groups that attract specific adsorbates (such as aromatics,cyclic and optional oxygenates) that are present in the onboard fuelsupply; and (2) using a molecular sieve to selectively pass certainsmaller (that is to say, linear) molecules while retaining larger (thatis to say, branched) ones. Examples of the first type of adsorbentinclude activated carbon, silica, and alumina, as well as some types ofzeolites and functionalized porous material in general, while examplesof the second type include zeolites, metal organic frameworks andstructured porous material. Within the present context, a fuel is deemedto be octane-rich when it has a concentration of iso-octane(2,2,4-trimethylpentane, C₈H₁₈) or equivalent anti-knocking agent thatis greater than that of the readily-available market fuel from which oneor more separation activities have been employed. By way of example, afuel would be considered to be octane-rich if it had a research octanenumber (RON) of greater than about 91-92 or an anti-knock index (AKI) ofgreater than about 85-87 for a so-called regular grade unleaded fuel,with respectively slightly higher values for mid-grade unleaded fuel andpremium unleaded fuel. Within the present context, it will be understoodthat there are regional variations in the values of RON, AKI or otheroctane or cetane indicia, and that the ones expressly discussed in theprevious sentence contemplate a United States market. Nevertheless, suchvalues will be understood to be suitably adjusted to take intoconsideration these regional variations, and that all such values aredeemed to be within the scope of the present disclosure within theirrespective region, country or related jurisdiction. As with octane, afuel is deemed to be cetane-rich when it has a concentration of n-cetane(n-hexadecane) (C₁₆H₃₄) or components with equivalent ignition delaycharacteristics that is greater than that of readily-available marketfuels. By way of example, a fuel would be considered to be cetane-richif it had a cetane number (CN) of greater than about 40-45 (for most ofthe United States market, with suitable variations elsewhere).

Referring first to FIG. 1, a vehicle 100 includes a chassis 110 with aplurality of wheels 120. Chassis 110 may either be of body-on-frame orunibody construction, and both configurations are deemed to be withinthe scope of the present disclosure. The passenger compartment 130 isformed inside the chassis 110 and serves not only as a place totransport passengers and cargo, but also as a place from which a drivermay operate vehicle 100. A guidance apparatus (which may include, amongother things, steering wheel, accelerator, brakes or the like) 140 isused in cooperation with the chassis 110 and wheels 120 and othersystems to control movement of the vehicle 100. An ICE 150 is situatedwithin an engine compartment in or on the chassis 110 to providepropulsive power to the vehicle 100 while a controller 170 interactswith ICE 150 to provide instructions for the latter's operation.

Referring next to FIG. 2, details associated with the structure andoperation of a portion of the ICE 150 and the controller 170 are shown.The ICE 150 includes an engine block 151 with numerous cylinders 152, acrankshaft 153 rotatably movable within the block 151, numerous cams 154responsive to movement of the crankshaft 153, a head 155 coupled to theengine block 151 to define numerous combustion chambers 156. The head155 includes inlet valves 157 and exhaust valves 158 (only one of eachis shown) that in one form may be spring-biased to move in response tothe crankshaft 153 through a corresponding one of the cams 154 that arecontrolled by either a crankshaft-driven chain, crankshaft-actuatedpushrods or pneumatic actuators (none of which are shown). An air inlet159 and an exhaust gas outlet 160 are in selective fluid communicationwith each of the combustion chambers 156 through a fuel injector 161,while a piston 162 is received in each respective cylinder 152 andcoupled to the crankshaft 153 through a connecting rod 163 so that thereciprocating movement of the piston 162 in response to an SI or CIcombustion taking place within the combustion chamber 156 is convertedby the pivoting movement of the connecting rod 163 and crankshaft 153 torotational movement of the crankshaft 153 for subsequent power deliveryto the remainder of a powertrain that is made up of the ICE 150 andtransmission, axles, differentials (none of which are shown) and wheels120. Although ICE 150 is shown without a spark ignition device (such asa spark plug) in a manner consistent with the various CI-based engineconfigurations (such as RCCI, HCCI or the like), it will be understoodthat in certain operating loads or conditions such as low loads, coldstarts and associated warm-ups, such a spark ignition may be used(possibly in conjunction with some throttling) to increase the flamepropagation combustion rate while keeping lower cylinder pressures.

In one form, ICE 150 is configured as a gasoline compression ignition(GCI) engine that can be operated with a gasoline-based fuel. In suchcase, the presently-disclosed fuel system may be used to achieve CODthrough operation on various fuels, including market gasoline, gasolinewithout an oxygenate or related anti-knock compound (also referred to asbase gasoline) or gasoline with one of the many types of alkyls,aromatics or alcohols. In one non-limiting example, such fuel may have aboiling temperature in the range of ambient to about 200° C. Unlike anSI mode of operation where the fuel is substantially injected during thefour-cycle operation's inlet stroke, a GCI mode substantially injectsthe fuel during the compression stroke. In one form, the fuel and airare not fully mixed, which permits phasing of the combustion process tobe controlled by the injection process. Moreover, the ignition delaypermitted by gasoline-based fuels versus diesel-based fuels will allowfor the partially premixed fuel and air to become more mixed duringcompression, which in turn will leave to improvements in combustion.Gasoline-based market fuels with some amount of fuel and air premixinghelps ensure suitable fuel-air equivalence ratios for various engineloads and associated fuel injection timing scenarios. Thus, whenconfigured as a GCI engine, ICE 150 using a fuel in the gasolineautoignition range (where for example, the RON is greater than about 60and the CN is less than about 30) can provide relatively long ignitiondelay times compared to conventional diesel fuels. This in turn can leadto improved fuel-air mixing and related engine efficiency, along withlower soot and NOx formation; this latter improvement leads in turn to asimplified exhaust gas treatment system since the emphasis is now onoxidizing hydrocarbons and carbon monoxide in an oxygen-rich environmentrather than trying to simultaneously control NOx and soot. Moreover,when operated as a GCI engine, ICE 150 requires lower fuel injectionpressures than diesel-based CI engines.

Furthermore, when configured as a GCI engine, ICE 150 may take advantageof gasoline-based market fuels that require lower amounts of processing;in one form, the fuel may be in the form of gasoline with anintermediate RON of between about 70 and 85. Such octane concentrationscould then be adjusted via OOD or COD through the operation of the fuelsystem 200 that is discussed in more detail elsewhere in thisdisclosure.

Moreover, unlike HCCI modes of operation where the fuel and air is fullypremixed prior to introduction into the combustion chamber 156, the GCIembodiment of ICE 150 will permit CI operation under higher engine loadsand compression ratios without concern over engine knocking.Furthermore, by permitting in-cycle control of the combustion phasing,an ICE 150 configured as a GCI can take advantage of fuel injectiontiming in order to make it easier to control the combustion processcompared to an HCCI configuration where the combination of temperatureand pressure inside the cylinder may not be precisely known.

In another form, ICE 150 is configured as an SI engine that can beoperated with a gasoline-based fuel. In this case, thepresently-disclosed fuel system may be used to achieve OOD throughoperation on various fuels, including market gasoline, gasoline withoutan oxygenate or related anti-knock compound or gasoline with one of themany types of alkyls, aromatics or alcohols.

Controller 170 is used to receive data from sensors S and providelogic-based instructions to the various parts of the fuel system 200that will be discussed in more detail later. As will be appreciated bythose skilled in the art, controller 170 may be a singular unit such asshown notionally in FIGS. 1 and 2, or one of a distributed set of unitsthroughout the vehicle 100, this latter configuration as shownnotionally in FIG. 3. In one configuration, controller 170 may beconfigured to have a more discrete set of operational capabilitiesassociated with a smaller number of component functions such as thoseassociated solely with the operation of the fuel system 200. In such aconfiguration associated with only performing functions related tooperation of the fuel system 200, the controller 170 may be configuredas an application-specific integrated circuit (ASIC). In anotherconfiguration, controller 170 may have a more comprehensive capabilitysuch that it acts to control a larger number of components, such as theICE 150, either in conjunction with or separately from the fuel system200. In this configuration, the controller 170 may be embodied as one ormore electronic control units (ECUs). It will be appreciated that ASICs,ECUs and their variants, regardless of the construction and range offunctions performed by the controller 170, are deemed to be within thescope of the present disclosure.

In one form, controller 170 is provided with one or more input/output(I/O) 170A, microprocessor or central processing unit (CPU) 170B,read-only memory (ROM) 170C, random-access memory (RAM) 170D, which arerespectively connected by a bus 170E to provide connectivity for a logiccircuit for the receipt of signal-based data, as well as the sending ofcommands or related instructions to one or more of the components withinICE 150, one or more components within fuel system 200, as well as othercomponents within vehicle 100 that are responsive to signal-basedinstructions. Various algorithms and related control logic may be storedin the ROM 170C or RAM 170D in manners known to those skilled in theart. Such control logic may be embodied in a preprogrammed algorithm orrelated program code that can be operated on by controller 170 and thenconveyed via I/O 170A to the fuel system 200. In one form of I/O 170A,signals from the various sensors S are exchanged with controller 170.Sensors may comprise pressure sensors, temperature sensors, opticalsensors, acoustic sensors, infrared sensors, microwave sensors, timersor other sensors known in the art for receiving one or more parametersassociated with the operation of ICE 150, fuel system 200 and relatedvehicular components. Although not shown, controller 170 may be coupledto other operability components for vehicle 100, including thoseassociated with movement and stability control operations, whileadditional wiring such as that associated with a controller area network(CAN) bus (which may cooperate with or otherwise be formed as part ofbus 170E) may also be included in situations where controller 170 isformed from various distributed units.

In situations where the controller 170 is configured to provide controlto more than just the fuel system 200 (for example, to the operation ofone or more of the ICE 150 or other systems within vehicle 100), othersuch signals from additional sensors S may also be signally provided tocontroller 170 for suitable processing by the control logic; one suchexample may include those signals where combustion data from the ICE 150is provided for control over the mixing or related delivery of the fueland air. Likewise, in a manner consistent with various modes of ICE 150operation, controller 170 may be programmed with drivers for variouscomponents within ICE 150, including a fuel injector driver 170F, aspark plug driver (also called a spark ignition driver, for SI modes ofoperation) 170G, engine valve control 170H and others that can be usedto help provide the various forms of fuel introduction to the combustionchamber 156, including those associated with a multiple-late-injection,stratified-mixture, low-temperature combustion (LTC) process as a way topromote smooth operation and low NOx emissions of ICE 150 over asubstantial entirety of its load-speed range. Within the presentcontext, load-speed mapping of ICE 150 may be used to identify operatingregions such as those used during cold starts and ICE 150 warm-up, lowICE 150 loads, medium ICE 150 loads and high ICE 150 loads, wherecorrespondingly lower amounts of exhaust gas re-breathing takes placethrough manipulating the overlap of the intake valve 157 relative to theexhaust valve 158, possibly in conjunction with other approaches such asexhaust gas recirculation (EGR) to help provide one or more ofcombustion control, exhaust gas emission reductions, or otheroperability tailoring for ICE 150.

In addition to providing instructions for combustion control, emissionreductions or the like, controller 170 interacts with conduit 210 andvarious actuators, valves and related components to control theoperation of the delivery of a market fuel from an onboard fuel supplytank 220, regenerator 230, separation unit 240 and enriched product tank250 in order to effect the production of OOD or COD required to operateICE 150 for a given set of load and related operating conditions. In oneform of CAN, the controller 170 could manage the fuel flow from eitherthe fuel tank 220 or the enriched product tank 250 to the combustionchamber 156 where the two fuels corresponding to OOD or COD are injectedseparately, or by blending prior to being introduced into the combustionchamber 156 at different ratios depending on load, speed and otheroptional parameters associated with operation of ICE 150.

In particular, controller 170 is useful in promoting customizable fuelinjection and subsequent combustion strategies for various CI engineconfigurations. For example, when used in conjunction with a GCI-basedengine, the controller 170 may instruct the fuel to be injected in astaged manner late in the compression phase of the engine's four-cycleoperation. In this way, the fuel charge may be thought of as having bothlocally stoichiometric and globally stratified properties.Significantly, because an octane-rich fuel (for example, gasoline) has ahigher volatility and longer ignition delay relative to a cetane-richfuel (for example, diesel), by introducing the octane-rich fuel into thecombustion chamber 156 relatively late in the compression stroke andtaking advantage of the fuel's inherent ignition delay (which helps topromote additional fuel-air mixing), combustion does not commence untilafter the end of the injection. To achieve a desirable degree ofstratification, multiple injections may be used. By operating under theLTC conditions that are associated with stratified fuel combustion, GCIengines can have significantly reduced NOx production and soot emissionswhile achieving diesel-like thermal efficiencies. Moreover, such anapproach permits the vehicle 100 to use an onboard market fuel with alower octane than would otherwise be used. This is beneficial in thatsuch fuel requires a smaller amount of processing than conventionalgasoline and diesel fuels; this in turn reduces the entire well-to-tankemissions of other undesirable substances, such as CO₂.

In addition to a GCI engine, such instructions as provided by controller170 are particularly beneficial for the multiple-late injection strategyused for the delivery of fuel in RCCI or related modes of operation ofICE 150, as such delivery is optimized when it coincides with varioussequences in the compression stroke that can be measured by sensors S asthey detect crank angle degree (CAD) values from the crankshaft 153 tohelp control when auto-ignition occurs. Within the present context, theposition of the piston 162 within the cylinder 152 is typicallydescribed with reference to CAD before or after the top dead center(TDC) position of piston 162. The controller 170 may also base suchdelivery strategies on other ICE 150 operating parameters such as thepreviously-mentioned load and engine speed, as well as the number oftimes such injection is contemplated. For example, CAD from 0° to 180°corresponds to the power stroke, with 0° representing TDC and 180°representing bottom dead center (BDC). Likewise, CAD from 180° to 360°represents an exhaust stroke with the latter representing TDC. Moreover,CAD from 360° to 540° represents an intake stroke with BDC at thelatter. Furthermore, CAD from 540° to 720° represents a compressionstroke with TDC at the latter. By way of example, the controller170—when used in a 6-cylinder engine—would have ignition taking placeevery 120° of crankshaft 153 rotation, that is to say three ignitionsper every revolution of ICE 150. Thus, when ignition has taken placeeach of the six cylinders one time, the crankshaft 153 has rotated twiceto traverse 720° of rotary movement. Likewise, if ICE 150 wereconfigured as a 4-cylinder engine, the ignition would take place every180° of crankshaft 153 rotation. In one form, one of the sensors S maybe a crank sensor to monitor the position or rotational speed of thecrankshaft 153. The data acquired from such a crank sensor is routed tothe controller 170 for processing in order to determine fuel injectiontiming and other ICE 150 parameters, including ignition timing for thosecircumstances (such as cold startup, and the ensuing warm-up) where aspark ignition device is being used. Sensors S such as the crank sensormay be used in combination with other sensors S (such as thoseassociated with valve 157, 158 position) to monitor the relationshipbetween the valves 157, 158 and pistons 162 in ICE 150 configurationswith variable valve timing. Such timing is useful in CI modes ofoperation of ICE 50 in that it can close the exhaust valves 158 earlierin the exhaust stroke while closing the intake valves 157 earlier in theintake stroke; such operation as implemented by controller 170 can beused to adjust the effective compression ratio of ICE 150 in order toobtain the required temperature and pressure associated with CIcombustion. Likewise, when SI combustion is required, the controller 170may instruct the valves 157, 158 to reduce the compression ratioconsistent with SI operation. Likewise, the controller 170 may—dependingon the need of ICE 150—provide auxiliary sparking for fuel preparation(such as the generation of free radicals in the air-fuel mixture).Sensed input (such as that from various locations within ICE 150,including CAD from the crankshaft 153, as well as those fromdriver-based input such as the accelerator of guidance apparatus 140)may be used to provide load indicia. Likewise, in addition to suitableadjustment of the valves 156, 157, balanced fuel delivery from each ofthe enriched product tank 250 with pressurizing forces provided by oneor more fuel pumps 260 may be achieved by controller 170 depending on ifICE 150 is in a CI mode or an SI mode of operation. Although there isonly one pump 260 shown (immediately upstream of the fuel injector 161)in an attempt to keep visual clarity within the figure, it will beappreciated that additional pumps 260 may be placed in other locationswithin conduit 210 in order to facilitate the flow of fuel through thefuel system 200, and that all such variants are within the scope of thepresent disclosure.

The controller 170 may be implemented using model predictive controlschemes such as the supervisory model predictive control (SMPC) schemeor its variants, or such as multiple-input and multiple-output (MIMO)protocols, where inputs include numerous values associated with thevarious post-combustion exhaust gas treatment components, sensors S(such as exhaust gas temperature sensor, O₂ sensor, NOx sensor, SOxsensor or the like), estimated values (such as from the lookup tables orcalculated algorithmically) or the like. In that way, an output voltageassociated with the one or more sensed values from sensors S is receivedby the controller 170 and then digitized and compared to a predeterminedtable, map, matrix or algorithmic value so that based on thedifferences, outputs indicative of a certain operational condition aregenerated. These outputs can be used for adjustment in the variouscomponents within the purview of the controller 170, such as theremaining components associated with fuel system 200.

As mentioned above, in one form, controller 170 may be preloaded withvarious parameters (such as atmospheric pressure, ambient airtemperature and flow rate, exhaust gas temperature and flow rate or thelike) into a lookup table that can be included in ROM 170C or RAM 170D.In another form, controller 170 may include one or more equation- orformula-based algorithms that permit the processor 170B to generate asuitable logic-based control signal based on inputs from varioussensors, while in yet another form, controller 170 may include bothlookup table and algorithm features to promote its monitoring andcontrol functions. Regardless of which of these forms of data andcomputation interaction are employed, the controller 170—along with theassociated sensors S and associated flow control conduit 210—cooperatesuch that as an operating load on the ICE 150 varies, a suitableadjustment of the market fuel that is present in the onboard fuel supplytank 220 may be made to provide the amount of octane or cetaneenrichment needed for such operating load by mixing the onboard marketfuel with one or the other of the product fuels from the enrichedproduct fuel tank 250.

One parameter of ICE 150 that may be preloaded into or generated bycontroller 170 is the mean effective pressure (MEP). In one form, MEPmay be used to correlate ICE 150 operating conditions to fuel needs andthe various forms of multiple-late injection strategies discussedpreviously for various CI engine configurations. MEP—including itsvariants indicated mean effective pressure (IMEP), brake mean effectivepressure (BMEP) or friction mean effective pressure (FMEP)—provides avalue of the ability of a particular ICE 150 to do work without regardto the number of cylinders 152 or related ICE 150 displacement.Moreover, it provides a measure of the pressure corresponding to thetorque produced so that it may be thought of as the average pressureacting on a piston 162 during the different portions of its four cycles(inlet, compression, ignition and exhaust). In fact, MEP is a betterparameter than torque to compare engines for design and output becauseof its independence from engine speed or size. As such, MEP provides abetter indicator than other metrics (such as horsepower) for engines inthat the torque produced is a function of MEP and displacement only,while horsepower is a function of torque and rpm. Thus, for a givendisplacement, a higher maximum MEP means that more torque is beinggenerated, while for a given torque, a higher maximum MEP means that itis being achieved from a smaller ICE 150. Likewise, higher maximum MEPmay be correlated to higher stresses and temperatures in the ICE 150which in turn provide an indication of either ICE 150 life or the degreeof additional structural reinforcement in ICE 150. Significantly,extensive dynamometer testing, coupled with suitable analyticalpredictions, permit MEP to be well-known for modern engine designs. Assuch, for a CI engine, MEP values of about 7.0 bar to about 9.0 bar aretypical at engine speeds that correspond to maximum torque (around 3000rpm), while for naturally aspirated (that is to say, non-turbocharged)SI engines, MEP values of about 8.5 bar to about 10.5 bar are common,while for turbocharged SI engines, the MEP might be between about 12.5bar and about 17.0 bar.

Likewise, MEP values may be determined for various operating regimes forICE 150. Such operating regimes may include low power or load(including, for example, engine idling conditions) that is one formcorresponds to a MEP of up to about 1.0 bar, in another form of an MEPof up to about 2.0 bar. Likewise, such operating regimes may includenormal (or medium) power or load that is one form corresponds to a MEPof between about 2.0 bar to about 5.0 bar, in another form of an MEP ofbetween about 2.0 bar and about 6.0 bar, in another form of an MEP ofbetween about 2.0 bar and about 7.0 bar. Moreover, such operatingregimes may include a high power or load that is one form corresponds toa MEP of about 7.0 bar and above, in another form of an MEP of about 8.0bar and above, in another form of an MEP of about 9.0 bar and above, andin another form of an MEP of about 10.0 bar and above.

As will be understood, these and other MEP values may be input into asuitably-mapped set of parameters that may be stored in a memoryaccessible location (such as the lookup tables mentioned previously) sothat these values may be used to adjust various ICE 150 operatingparameters, as well as for the controller 170 when acting in adiagnostic capacity. In such case, it may work in conjunction with someof the sensors S, including those that can be used to measure cylinder152 volume (such as through crankshaft 153 angle or the like).

Referring next to FIG. 3, details associated with managing the heatbalance associated with performing onboard COD and OOD operations whileavoiding complicated system redundancy for fuel system 200 is shown.Significantly, by taking advantage of existing onboard fuel delivery andICE 150 operating infrastructure, any on-vehicle cooling and heatingneeded to promote the various adsorbing and regenerating activities canbe achieved without requiring additional equipment orefficiency-decreasing modes of operation of the ICE 150. The fuel system200 includes a network of pipes, tubing or related flow channels—alongwith various valves to preferentially permit or inhibit the flow of theonboard fuel and its byproducts of fuels, depending on the need—thatmake up conduit 210.

The fuel supply tank 220 is used for the storage of the market fuel thatit receives via inlet 221 from a conventional fuel pump such as thoseused in retail filling stations. In one form—such as that associatedwith GCI operation—the market fuel may comprise an even lower-grade ofgasoline-based fuel, such as the previously-mentioned intermediate RONgasoline. Significantly, the fuel supply tank 220 also acts as a heatexchanger that is made up of numerous nested housings that definehollow, volumetric regions making up a first compartment 222, a secondcompartment 224 and a third compartment 226, all of which are used forthe storage and selective conveyance of various forms of the fuel thatis onboard vehicle 100. In one form, the housing used for the firstcompartment 222 defines the outermost structure, and as such mayfunction as a containment vessel or related structure for the housingsthat make up the other two compartments. More particularly, in the formshown, this outermost structure that corresponds to the firstcompartment 222 allows the fuel supply tank 220 to use a concentricarrangement between the first compartment 222 and the inner twocompartments 224 and 226; such a closely-packed storage and heatexchange configuration is particularly appropriate for small or compactpassenger-based configurations of vehicle 100 (such as smaller two-seatcars, two-door coupes and four-seat sedans) that do not have the luxuryof additional space such as that inherent in larger passenger vehicles,commercial vehicles or industrial vehicles. While the housing that makesup the first compartment 222 is presently shown in generally cylindricalform, it will be appreciated that other suitable fuel containmentstructural forms or shapes may also be employed, and that as long asthey permit the heat exchange functions discussed in the presentdisclosure, all such variants are within the scope of the presentdisclosure.

The second compartment 224 is used for the storage of the octane-richfuel component that has been produced by the sorption of a portion ofthe onboard market fuel that has been conveyed from the firstcompartment 222 to the separation unit 240 the details of which arediscussed in more detail elsewhere in this disclosure. Within thepresent context, the octane-rich fuel component achieves such statuswhen it is placed in a form that it can be introduced into thecombustion chamber 156 for subsequent combustion; in one form, suchoctane-rich fuel component is in a liquid form after having beencondensed from a vaporized form after being desorbed by the separationunit 240. In one form, the housing that makes up the second compartment224 is shaped with an elongate axial dimension in an manner similar tothat of the housing that makes up the first compartment 222, while ofsmaller outer dimensions in order to enable it to fit within theinternal volume defined by the housing that makes up the firstcompartment 222. In such a configuration, when the first compartment 222is filled with onboard market fuel, the exterior surface of the housingthat makes up the second compartment 224 is substantially immersedwithin such fuel. In this way, the fuel system 200 may take advantage ofany temperature differences between the fuels contained in these twocompartments 222, 224 in order to help generate the octane-rich fuelcomponent for selective use in combustion chamber 156. Significantly,the first and second compartments 222, 224 are fluidly isolated from oneanother such that the enriched levels of octane present within thelatter compartment are not diluted by the non-enriched levels presentwithin the former.

The third compartment 226 is used for additional storage of any of theoctane-rich fuel component that has been produced by the at leastpartial condensation within the second compartment 224 of the desorbateproduced in the separation unit 240. More particularly, because thehousing making up the third compartment 226 is nested within theinternal volume defined by the second compartment 224, it issubstantially immersed within such the octane-rich fuel component in amanner similar to that of the second compartment 224 relative to thefirst compartment 222 as previously discussed. As shown, the housingthat makes up the third compartment 226 is in the form of a bundle ofindividual tubes that extend linearly along the elongate dimensiondefined by that of the first and second compartments 222, 224. In oneform, the tubes may be open at both ends such that the tubes may act asa temporary storage for the octane-rich fuel component, as well as aconduit or related flowpath to deliver such fuel component from thesecond compartment 224 to the combustion chamber 156, either directly orthrough a manifold 228 that may be included as an end cap for the secondcompartment 224. Furthermore, it will be appreciated that the tubenumber and size can be adjusted to fulfill the designed cooling orcondensation requirements of the octane-rich fuel component, as well asof any remaining vaporized octane-rich adsorbate.

By such construction, the second and third compartments 224, 226 form ashell-and-tube heat exchanger configuration where the housing of thesecond compartment 224 acts as a shell-like fluid container for both thevaporized form of the adsorbate from the separation unit 240 and theoctane-rich fuel component that results from condensation of thevaporized adsorbate, as well as a fluid vessel around the tube bundlethat makes up the housing of the third compartment 226. Likewise, thehousing that makes up the first compartment 222 may be considered ashell that acts as a fluid vessel around the tube-like housing of thesecond compartment 224. In the larger shell-and-tube arrangement definedby the first and second compartments 222, 224, the larger vesselprovides a relatively large heat sink for condensing the vaporizedadsorbate that is created during adsorbent regeneration in theseparation unit 240 and conveyed to the second compartment 224. In thesmaller shell-and-tube arrangement defined by the second and thirdcompartments 224, 226, the third compartment 226 may also serve as asupplemental heat sink to the larger in situations where some residualoctane-rich fuel component resident within one or more of the individualtubes. Such a situation might arise where the vehicle 100 has not beenin an operational state for a prolonged period (such as overnight) oftime that is sufficient to have allowed the fuel component containedwithin to cool down.

Thus, the concentrically-arranged shell-based structural, fluid andthermal cooperation between the three compartments 222, 224 and 226 isconstructed in a such a manner to functionally replace three separateunits (namely, a conventional vehicle fuel tank, separate regeneratedfuel condenser and the condensed fuel storage tank) in order to helppromote a more compact fuel system 200. During operation of the vehicle100, the onboard fuel that resides in the first compartment 222 coolsthe vaporized adsorbate and any octane-rich fuel component (ascondensate) that is present inside the second compartment 224. Uponoperation of a pump 260 that is disposed within conduit 210, at least aportion of the onboard fuel is made to exit the first compartment 222 tobe routed into either the adsorption-desorption chambers 241, 242 of theseparation unit 240, or directly to the combustion chamber 156,depending on which operational condition for ICE 150 is determined bythe controller 170. In one form, any such condensed liquid may be placedin selective (rather than constant) fluid communication with thedesorbed vapor because there may be some modes of operation of ICE 150(such as that mentioned previously in conjunction with certain drivingcycles) where it is desirable to have the desorbed octane or theremainder cetane be sent directly to the combustion chamber 156 for use.

Once the fuel is placed in fluid contact with one of the sorptionchambers 241, 242 (again, as determined by the controller 170, with thepossible input from sensors S to determine whether one or the other ofthe sorption chambers 241, 242 is in a state of saturation, hightemperature or the like), some of the onboard fuel is adsorbed, whilesome leaves the separation unit 240 to an enriched product tank 250until needed. One or more of valves V1, V2, V3 and V4 may be manipulated(also through controller 170) to help effect fuel flow to a preferredlocation. Within the present context, the various valves V1, V2, V3 andV4 (as well as pump or pumps 260) make up a portion of the conduit 210;with regard to such valves, it will be appreciated that there may begreater or fewer in number, depending on the precise configuration ofconduit 210, and that all such variants are deemed to be within thescope of the present disclosure. For example, in one form of operation,these or other valves (not shown) may be used to alternate between thesorption chambers 241, 242 so that they are selectively switched toprovide batch-like processing.

The adsorbed portion of the onboard fuel is maintained on the adsorbentsurface of the respective sorption chamber 241, 242 until either thechamber becomes saturated or the chamber temperature becomes highenough. In the case of saturation, it may be necessary to extract theadsorption heat (such as through a suitable coolant). In addition, whenthe incoming flow of onboard fuel is switched to the other of thesorption chambers 241, 242, a heat supply (from either the car coolantor the exhaust gas) is circulated into the respective chamber to theregenerator 230 that acts as a vaporizing heat exchanger for theadsorbed fuel. The regenerated fuel vaporizes, causing it to risevertically upward to enter into the second compartment 224 via portionof conduit 210 in order to promote significant heat transfer. In oneform, such heat transfer causes condensation of the regenerated fuelvapor by exchanging its heat content with the onboard fuel that isresident within the first compartment 222 of the main tank. As discussedpreviously, additional condensation of the regenerated fuel vapor maytake place in situations where the various tubes of the thirdcompartment 226 may already contain stored (and previously condensed)octane-rich fuel component such as that associated with a prolongedperiod of vehicle 100 and fuel system 200 inactivity. This has theeffect of providing a so-called “double side cooling” on the portion ofthe fuel that is present within the second compartment 224. Thisimproved amount of heat transfer allows the size of the heat exchangestructure to be reduced.

The octane-rich fuel component may then be directed to storage untilneeded. In one form, a separate product tank (not shown, but similar inconstruction to enriched product tank 250) may be included, although byallowing one or both of the second and third compartments 224, 226 (aswell as the portions of conduit 210 that are fluidly downstream of thesecond and third compartments 224, 226) to act as storage vessels in anattempt to minimize the complexity and volumetric impact of theproduction of the octane-rich fuel component. Likewise, the ICE 150 maybe made—through the cooperation of the fuel system 200 and thecontroller 170—to receive the octane-rich fuel component that is storedin the tube bundles of the third compartment 226, the cetane-rich fuelcomponent that resides in the enriched product tank 250 (or the adjacentportion of the conduit 210), or the onboard (that is to say, market)fuel that is present in the first compartment 222. As discussedelsewhere within the present disclosure, the controller 170 may also beused to ensure suitable vehicle 100 operation, especially in situationswhere the octane-rich or cetane-rich fuel components are not enough toprovide ample combustible fuel to the ICE 150 in certain operatingconditions, such as at the beginning of the driving cycle, if the demandis higher than expected, or where no heat is available onboard to desorb(that is to say, vaporize) the fuel (such as during a cold start).

In one form, it may be beneficial to maintain the temperature of theonboard fuel that is present within the first compartment within aprescribed range. One way to achieve this is to use an injector (notshown) and an insulated part (not shown) in the volumetric regionbetween the first and second compartments 222, 224. In suchconstruction, the injector pulses the needed amount of the onboard fuelfrom an insulated part of the first compartment 222 to uninsulated part,where such insulation difference can be in the form of lowthermal-conductivity materials appropriately placed, while in anotherform as one or more baffles distributed through the volumetric regiondefined within the first compartment 222. Regardless of the form ofinsulation, it promotes a more homogeneous heat transfer, as well as ahigher amount of contact between the fuel and the heat exchange surfacearea of the housings that define both the first and second compartments222, 224.

Significantly, the fuel system 200 may operate using residual thermalenergy from the vehicle 100, such as that from the waste heat of thecombustion process that takes place within the combustion chamber 156 ofICE 150. This use of existing heat helps further promote overall duelsystem 200 compactness by reducing component redundancy. As mentionedpreviously, a batch-like processing approach may be made to take placewithin the separation unit 240 where the pair of sorption chambers 241,242 are placed in thermal communication with the regenerator 230, allwithin a housing or related containment structure. Thus, upon receipt ofthe market (that is to say, onboard) fuel from the fuel supply tank 220through conduit 210 and an optional preheater (not shown), the first ofthe sorption chambers 241 is sized and shaped to fluidly receive anaromatic (that is to say, octane-rich) compound such that contact of thearomatic on the surface of sorption chamber 241 results in the creationof an octane-rich adsorbate for OOD, such as by the preferential actionof a suitable functional group contained within or formed on the surfaceof the adsorbent that makes up the sorption chamber 241 as will bediscussed in more detail later in this disclosure. The two-chamberconstruction of the separation unit 240 is such that while octane-richadsorption is taking place in sorption chamber 241, any adsorbent thatwas previously saturated in the other sorption chamber 242 isregenerated by exposure of the adsorbate to elevated temperatures (suchas from exhaust gas from ICE 150 or a hot coolant from a radiator-basedcooling system or the like) through the regenerator 230. With adifferent choice in adsorbent in the sorption chambers 241, 242, acetane-rich adsorbate (rather than octane-rich adsorbate) can be formedin a comparable manner for COD through the use of a size-selectiveadsorbent. In one form, such OOD-specific and COD-specific activity maybe achieved through multi-stage configurations of separation unit 240where sequentially-placed units each with one or more of the sorptionchambers 241, 242 may be arranged, each configured with suitableaffinity-based or size-selective adsorbents. Thus, in one form, by theoperation of the adsorbent that is configured to preferably retainaromatics or related functionality-based fuel components such asoxygenates or double bond-based alkyls, much of the octane-rich portionof the market fuel forms on the surface of the sorption chamber 241while much of the cetane-rich portion passes through to become aremainder that can be then conveyed (as shown) to the cetane-enrichedproduct tank 250 or back (not shown) to the fuel supply tank 220.Although presently shown as a separate cetane-enriched product tank 250,it will be appreciated that—depending on the latency or resident periodassociated with the presence of the cetane-rich remainder within theportion of conduit 210 that extends from the point of discharge from theseparation unit 240 to the introduction of such remainder into thecombustion chamber 156 of internal combustion engine 150—such portion ofconduit 210 may be sufficient to in effect emulate the storagecapability of cetane-enriched product tank 250 such that it is thefunctional equivalent. In such circumstances, that portion of theconduit 210 may be deemed to be a cetane-enriched product tank 250within the meaning of the present disclosure.

Within the present context, the terms “adsorb”, “adsorbate” and theirvariant includes those portions of the onboard fuel that interact bysurface retention (rather than by bulk absorption) with the adsorbentthat makes up the sorption chambers 241, 242, while the terms “desorb”,“desorbate” and their variant includes those portions of the adsorbatethat are subsequently liberated from the adsorbent as a result of someregenerating action. In one non-limiting form, such desorbing may takeplace by the application of a quantity of heat to the sorption chambers241, 242 sufficient to vaporize the adsorbate. Furthermore, it will beappreciated that unlike chemical reactions, adsorption is a physicalphenomenon, although in certain circumstances the term chemi-sorptionmay be used. Likewise, within the present context, the remainder (alsoreferred to as the filtrate) is the portion of the market fuel beingexposed to the adsorbent in the sorption chambers 241, 242 that does notget adsorbed, such as through one or both of the previous-discussedfunctional group (affinity-based) or molecular sieve (size-selective)operations.

The two-chamber construction of the separation unit 240 is conducive tothe batch processing of octane-enriched or cetane-enriched fuel. Inparticular, the two sorption chambers 241, 242 may be operated in aparallel manner such that while one is being used as an adsorbent topreferentially capture a thin film of octane-rich adsorbate, the othermay be exposed to the latent heat from the operation of ICE 150 in orderto regenerate the adsorbent by desorbing the previously-collectedadsorbate, after which the roles of the two chambers 241, 242 arereversed through manipulation by controller 170 of valves (not shown)that make up part of conduit 210. In order to have a compact separationunit 240 that does not add much to the weight of vehicle 100, theadsorbent type is selected to give a high surface area-to-volume ratioby exploring the geometry and structure of the adsorbent particles andbed that makes up the two sorption chambers 241, 242. In particular,higher surface area leads to higher adsorption capacity and smallerseparation unit 240 size, which in turn promotes ease of systemintegration. In another context, the use of the regenerator 230 and thebatch process associated with selective adsorption and regeneration ofthe sorption chambers 241, 242 helps to maintain the separation unit 240within a desired design temperature range. It will be appreciated thatthe desired temperature range depends on the solid sorbent being usedand its interaction with the targeting components of the fuel. Forexample, oxygenates adsorption is stronger than linear alkanes anddesorbing them will require a higher temperature. Likewise, if thedesorption is by vaporization, then the temperature will be equal to theboiling point of the desorbed components plus 5° C. to 20° C. Foraromatics in the gasoline range, desorption will take place above 110°C. Moreover, if the desorption is by solvent, then the temperature ofthe sorbent will remain around the ambient temperature, although thesolvent is separated from the target component by flashing at atemperature close to the boiling point of the solvent. For sizeselective separation, the temperature of the sorbent will likewiseremain around the ambient temperature.

As mentioned previously, various forms of stratified combustion may leadto the types of LTC that are beneficial to low-NO_(X) modes of operationof ICE 150. With regard to the use of OOD or COD for a CI engine, thefuel may be formed as a hybrid of a main fuel (for example, gasoline orother low-cetane variant) and an igniter fuel (for example, diesel orother high-cetane variant), where the location, frequency and timing ofintroduction of each varies by concept or configuration such as thosediscussed previously. For example, in one concept, a single high-octanefuel is introduced via direct injection during a compression stroke. Insuch case, the injection of the fuel takes places at a time relativelyretarded from conventional diesel injection timing to ensure adequatemixing. Since the overall combustion process is dominated byreactivity-controlled LTC, the resulting NOx and soot exhaust emissionstend to be very low. In another case, a single igniter fuel isintroduced via direct injection during the compression stroke in orderto promote cold-start and high-load operation where the overallcombustion process is dominated by diffusion-controlled mixing of thefuel at or near the piston 162 TDC movement. In still another case, adual injection regime introduces the main fuel via port fuel injectionearly in the compression stroke such that it is fully mixed with a freshair charge during the intake stroke, after which the igniter fuel isintroduced via direct injection as a way to control ignitability suchthat the overall combustion process is dominated by the spatiallywell-mixed high-octane fuel after the ignition of high-cetane fuel. Aswith the first case mentioned previously, such operation produces lowNOx and soot emissions, due at least in part to an overall lean mixture.In yet another case, the main fuel is introduced via direct injectionduring the compression stroke, while the igniter fuel is introduced viadirect injection near TDC to enable the ignition control; in this way,it provides a relatively robust mixture via improved thermal or spatialstratification. This in turn leads to low hydrocarbon, NOx and sootformation, at least for relatively low engine loads.

In one form, a so-called partial bypass may be used for intermittentcircumstances (such as cold starts, or where one of the two high-octaneor low-octane fuel tanks may be empty) such that a fraction of themarket fuel from the fuel supply tank 220 is provided directly to thecombustion chamber 156 without entering the separation unit 240. Thispartial bypass the operation of which may be established by controller170 helps promote a continuous supply of fuel to ICE 150, and that suchcontinuity is particularly useful under the intermittent operatingconditions mentioned previously. In particular, the controller 170 maybe used to manipulate various fuel delivery parameters, such as coolanttemperature, exhaust gas temperature, level of separated fuels, deliverytiming or the like for such transient operating situations. This helpspromote wider operating ranges reactivity differences between thehigh-octane and high-cetane fuel components, especially with regard toreducing NOx or soot emissions over a much wider range, thereby reducingthe likelihood of having to make a soot/NOx tradeoff.

Various fuel injection strategies can be utilized to enable optimumefficiency, reduced emissions and improved combustion robustnesscompared to conventional diesel-based cycles, including using EGR andreduced compression ratios. For example, EGR is used as a way to dilutethe mixture and decrease the combustion temperature as part of a largerLTC strategy. Likewise, lowering the compression ratio can help reduceengine friction loss, heat loss and hydrocarbon emissions.

As mentioned previously, in one form, the adsorbents used for thesorption chambers 241, 242 are configured as one or more functionalgroups presenting on the surface of the sorbent material such that theycomprise affinity-based sorbents. In another form, the adsorbents mayseparate adsorbates by their molecular shape such that they comprisesize-selective sorbents. For example, to target high-cetane fuelcomponents, the design would focus on separating linear or slightlybranched alkanes from aromatics, cyclic and highly branched alkanes.Stated another way, the solid sorbents discussed in the presentdisclosure can act in two mechanisms, where in a first, the adsorbent isselected to have functional groups that attract specific molecules suchas aromatics, cyclics and oxygenates (if present). The linear andslightly branched molecules (which may include cetane) are not adsorbedand pass through the pores of the sorption chamber 241, 242. The secondmechanism is based on the difference in the molecules sizes such thatlinear molecules (such as n-alkanes) may pass through the relativelyporous material while other molecules which have a larger dynamicdiameter are hindered from passing through most pores and accumulate inthe adsorption-based sorption chamber 241, 242. In this lattermechanism, a packed bed of size-selective sorbent is used for CODgeneration, as linear alkanes with high CN will go into smaller poreswhile the other components with larger molecular size will not, causingthese other components to come out first as a raffinate. In such case,the preferentially adsorbed linear alkanes could then be desorbed usingthermal energy such as discussed in the present disclosure in a mannersimilar to an affinity-based sorbent. In situations where the marketfuel onboard the vehicle 100 is gasoline—based, the thermal regenerationsuch as available through the operation of a heat exchanger such as thatdefined within the fuel supply tank 220 is particularly appropriate, asthe separated stream of fuel will tend to have a relatively highvolatility and associated low temperature boiling point. Examples of thefirst type of sorbents include: activated carbon, silica, and aluminabased sorbents as well as some types of zeolites and functionalizedporous material in general. Likewise, zeolites, metal organic frameworksand structured porous material may be made to act according to thesecond mechanism. As such, the sorption chambers 241, 242 may—inaddition to having batch processing capability through selectiveadsorbing and desorbing activities—be set up in stages (not shown) inthe manner previously discussed such that a first stage preferentiallyprovides affinity-based aromatic adsorption while a second stage actslike a size-selective molecular sieve. In this way, the first stageadsorbs octane while the second stage adsorbs cetane. Thus, whereasgasoline has relatively small aromatics with single benzene rings (suchas benzene, toluene and xylene), diesel fuel has larger aromatics in theform of polycyclic (or polynuclear) aromatic hydrocarbons (PAHs)including naphthalene and its derivatives. It is recognized that thereare some cetane-rich additives that have functional groups, thus, ifsome such additives are present, then affinity-based sorbents could beused as well for these components. As such—and depending on the needsassociated with a particular market fuel—the adsorbents useful in thesorption chambers 241, 242 may be selected with a high affinity forthese components specifically, and that the order, placement andconfiguration of each of the sorption chambers 241, 242 may beconfigured with the appropriate adsorbent depending on the constructionof fuel system 200. In one form, the higher the molecular weight of theadsorbent, the higher the adsorption capacity. Thus, differentadsorbents can be used to adsorb the low boiling point straight alkanesas a way to produce a fuel with different specifications. For instance,to adsorb certain aromatics, the adsorbent that makes up the sorptionchambers 241, 242 can be mesoporous (2-50 nm diameter) activated carbon,which in turn can lead to an average recovery of about 80%. An exampleof the anticipated adsorption capacity of some aromatic components foractivated carbon is listed in Table 1.

TABLE 1 Component mg/g-adsorbent Toluene 15 Naphthalene 451-methylnaphthalene 37

Other natural adsorbents (for example, coconut shell) may also be usedfor separating the desired components. In another form, the adsorbentbed of the sorption chambers 241, 242 may be made up of more than oneadsorbent in order to preferentially promote the adsorption of a desiredspecies. Regardless of the adsorbent bed choice, the performance isoptimized on various factors, including the adsorbent's capacity andselectivity, the concentration ratio of the market fuel (which providesindicia of the aromatics fractions), and how fast the regeneration anddesorption-based removal proceeds.

The selection of the ICE 150 and its associated fuel is dependent atleast in part on the properties of the fuel and the solid sorbentcontained within the sorption chambers 241, 242; such properties mayinclude the relative fractions in the market fuel, boiling temperaturesand sorbent separation mechanisms. For example, using an affinity-basedsorbent may be used to produce an OOD adsorbate for low boiling-pointfuels such as gasoline, while a size-selective sorbent may be used toproduce a COD adsorbate for such low boiling-point fuels. Inconfigurations where the separation unit 240 is arranged to havesequentially-placed units each with one or more of the sorption chambers241, 242 with affinity-based or size-selective adsorbents as discussedpreviously, it will be appreciated that the order of such separation maybe affinity-based first and size-selective second, or size-selectivefirst and affinity-based second, depending on the need.

Thus, for a compact and cost-effective vehicular propulsion system, asmaller fraction of fuel associated with the production of theoctane-rich or cetane-rich fuel components may be routed through alonger path within conduit 210 while the larger remaining or unseparatedfraction may be made to pass through a shorter path. In this way, thelength of the flowpath defined by the fuel system 200 components notused to perform such fuel enrichment may be kept relatively short,especially in view of the fact that the volume of high octane or highcetane fraction fuel components needed in OOD or COD operation isrelatively small compared to the remaining fraction of the market fuelthat is being supplied to the separation unit 240 or the ICE 150. In oneform, the amount of time that ICE 150 is operated under high load isrelatively small compared to total operating time. As such, a morecompact, low-cost fuel system 200 may be realized when the octane-richor cetane-rich stream is routed through the longer path (which in oneform may involve the separation of between about 20% to 30% of themarket fuel as an octane-rich or cetane-rich fuel stream). It is notedthat the general use of fuels for certain engine configurations may notbe available for all fuel forms at all fueling stations. For example,naphtha (that is to say, the light fuel fraction that results fromdistillation and boiling that takes place in the gasoline range fromabout ambient temperature to about 160° C.) typically has only betweenabout one and ten percent aromatics. Thus, in situations where anadditional CN boost for a particular COD use is required, these aromaticcomponents that represent the smaller fraction could be separated out,such as through the use of an affinity-based sorbent, as a way to ensurelower combustion temperature and associated lower NOx generation.

Likewise, in one form, the boiling range of the separated fuel stream iswithin a range that is compatible of heat exchange values that can beprovided by the operation of the ICE 150. Thus, when such a stream hasrelatively high volatility—such as the case when separating gasolinefractions—then the heat available onboard from the operation of ICE 150is enough to regenerate the sorbent. As such, using a gasoline-basedmarket fuel for GCI or SI modes of operation of ICE 150 may be employedso long as the boiling range of the adsorbate or remainder is compatiblewith the thermal environment being generated in the heat exchanger 243.

In using the regenerator 230, the controller 170 may instruct theswitching between fuel and fresh air flow between the two chambers 241,242 through one of three different techniques. In a first technique, asensor S is connected to the exit of the first sorption chamber 241 suchthat when the inlet and outlet liquid streams have an equal aromaticcontent as detected by sensor S (which in turn provides indicia ofsaturation in that no additional changes in the aromatic concentrationare occurring), the controller 170 in response to such an acquiredsignal switches the market fuel that is being delivered from the fuelsupply tank 220 to the second sorption chamber 242. In a secondtechnique, a timer is connected to the controller 170 to allow it toopen and close at certain time intervals (for example every 15 minutes)where the time intervals depend on the absorbent size and rate of theadsorption. In a third technique, sensor S may be a temperature sensorsuch that once the temperature at the respective sorption chamber 241,242 is no longer increasing (which in turn provides indicia of nofurther heat release due to adsorption), the controller 170 switches thefuel flow from the first sorption chamber 241 to the second sorptionchamber 242.

With particular regard to the partial bypass operational conditionmentioned previously, in certain operational conditions of ICE 150 (alsoreferred to as a first operational condition), it may be necessary forreliable operation to use an SI mode of operation, as at startup orother scenarios there are no exhaust gases or hot radiator fluidavailable to heat the adsorption cycle, or where there are nohigh-cetane or high-octane fuels present in the enriched product tank250. Furthermore, the fuel system 200 may employ self-automationfeatures to allow it to adjust itself according to the driving cycle.For example, at the beginning of a driving cycle, low RON fuel may beneeded; during this operational period, the controller 170 may instructthe various components that make up the conduit 210 to by route the flowof onboard fuel through the system 200 in order to leave the onboardfuel in its substantially original (that is to say, market-based) formsuch that no appreciable adsorption activity is undertaken. Likewise,during such early stage of the driving cycle (and related ICE 150operation) when the low RON fuel is being used, exhaust and other ICE150 residual heat starts to form, at which time such heat can be used toregenerate the adsorbed octane-rich portion of the onboard fuel throughvaporizing the octane-rich adsorbate that collects on the adsorbent thatmakes up the sorption chambers 241, 242. Furthermore, in situationswhere there is sufficient exhaust heat being generated by ICE 150operation, the absorption and regeneration will be at their fullcapacities; otherwise, the fuel system 200 can be made to work at apartial load using as much heat as is available to provide octane-richand cetane-rich fuel components. In this way, the fuel stream that isbeing conveyed from the first compartment 222 of fuel supply tank 220 isusually fed to the separation unit 240 where it is acted upon, except inthose ICE 150 operating regimes where there is an inadequate amount ofexhaust, residual or otherwise supplemental heat with which to promotethe regeneration of adsorbed portions of such onboard fuel. Furthermore,the partial bypass avoids otherwise undesirable latency periodsassociated with sudden driving conditions associated with speed or load,as well as those related to weather conditions. In such a partial bypassoperational condition, the controller 170 may instruct a fraction of themarket fuel from fuel supply tank 220 to be supplied directly to thecombustion chamber 156, without entering the separation unit 240. Thisfraction can be controlled and manipulated via different methods such astemperature of the coolant or exhaust gas, level of separated fuels,time or other variables. Two examples are presented to highlight thebenefits associated with partial bypass operation.

First, during startup of ICE 150 when no heat is available to operateadsorption cycle and no fuel fractions are available, the controller 170works together so that fuel flow may partially come from the LON fuelcomponent that is contained within the enriched product tank 250, whilethe main fuel portion comes from the fuel supply tank 220. If either ofthe enriched product tank 250 or the second and third compartments 224,226 of the fuel supply tank 220 is empty at any time (such as thatassociated with unexpected driving cycle conditions, lack of heatingneeded for desorption or insufficient air cooling), the controller 170may instruct one or more fuel pumps 260 (only one of which is shown) topressurize the market fuel being delivered from the fuel supply tank 220directly to the combustion chamber 156 as a way to at least partiallybypass the separation unit 240 to compensate for the shortage in thecetane-enriched product tank 250 or the second and third compartments224, 226 of the fuel supply tank 220.

Significantly, the fuel system 200 is designed to avoid usingsupplemental equipment, instead utilizing components that are alreadyoperating for other purposes, such as a fan (not shown) that movesambient air for cooling during the adsorption step, and the fuel pump260 (although even equipment like this may be reduced, simplified oreliminated in situations where common rail fuel injection may be used).In one form, the fuel injection pressures generated by the fuel system200 may be up to about 500 bar for gasoline direct injection, and up toabout 2500 bar for common rail diesel injection where this higherinjection pressure is used to expand the operating region ofdiesel-based CI engines in that it facilitates premixed CI combustion.In so doing, this latter pressure increase for diesel fuel-based enginesmay offset the needed robustness of construction and reductions incompression ratio and fuel ignition delay. As mentioned previously, thefuel system 200 takes significant advantage of latent heat associatedwith normal ICE 150 operation to perform its vaporization (that is tosay, desorption) activities in the separation unit 240.

Referring next to FIG. 4, an example is provided to demonstrate theapplicability of the proposed method and system with particular emphasison small adsorbent size and fast adsorption rate y for three differenttemperatures of 150° C., 180° C. and 210° C. for a 1000 cc zeoliteadsorbent sample with a Y-based framework; this size was chosen becauseit was deemed to be compatible with vehicular-based applications. Inparticular, the employed adsorbent is zeolite NaY with a geometricvolume of α-cages (0.294 cc/g) and β-cages (0.054 cc/g). The adsorptioncapacity of various aromatic molecules that are present in acommercially-available gasoline-based market fuel for this type ofadsorbent is shown in Table 2.

TABLE 2 Aromatic Adsorption Capacity Adsorption Capacity Component (ml/gNaY) (ml/cm³ NaY) Benzene 0.29 0.4 Toluene 0.28 0.39 m-Xylene 0.28 0.39Mesitylene 0.21 0.3 Average 0.265 0.37

Despite the fact that adsorption of aromatics using Y-based zeolitestends to be a relatively slow process, there is no need to wait for fullequilibrium as many of the aromatic species contained within the marketfuel reach a saturation level much more quickly. For example, toluene isadsorbed and reaches equilibrium within 20 minutes, with substantiallycomplete equilibrium occurring after about 1.0 to 1.7 hours. Moreover asshown, the adsorption rate y increases with temperature. This permitsthe adsorbate rate over the adsorption cycle to be easily estimated.Significantly, it demonstrates that various enriched fuel components canbe produced in a timely manner using adsorption-based equipment withheat exchange componentry that can meet the relatively small volumetricrequirements needed for placement within a vehicular package,particularly for compact and smaller passenger versions of vehicle 100.

Referring next to FIG. 5, the amount of octane-enriched fuel that can beseparated onboard by fuel system 200 that uses the zeolite-basedadsorbent with the properties set forth in previously-discussed Table 2and following Table 3 in the reactant chambers 241, 242 is shown. By wayof one example, vehicle 100 may be configured as a passenger vehiclethat consumes 6 liters of fuel per 100 kilometers averaging consumptionover city and the highway distances and running at an average speed of70 kilometers/hour; in such case, gasoline demand may be typically 4.5liters/hour.

By way of another example, vehicle 100 may be configured as a compactvehicle that consumes 1.6 liters/hour of 95 RON gasoline that includes30% aromatics consumed at the rate of 0.48 liters/hour. Moreparticularly, the aromatic molecules include toluene (0.192liters/hour), xylene (0.192 liters/hour), benzene (0.048 liters/hour)and mesitylene (0.048 liters/hour). The adsorbate amount is shown forthree notional cycle times of 10 minutes, 20 minutes and 100 minutes fora 1000 cc Y-based zeolite adsorber. When this fuel stream passes throughthe adsorbent bed that is formed on each of the reactant chambers 241,242, aromatic molecules separate and attract to the adsorbent particlesat different rates depending on the molecule shape, size or the like.

After only 10 minutes of operation, 6% of the regular gasoline separatesas high-octane gasoline with a 119 RON. Likewise, after only 20 minutes,12% of the regular gasoline separates into the 119 RON gasoline, whereascomplete equilibrium is attained after 160 minutes. The results indicatethat adsorption-based OOD can be employed for onboard applications interms of the system size and operation time.

TABLE 3 Unadsorbed Un- Time Flow Adsorbate fuel flow adsorbed (min)(l/h) RON Composition (l/h) fuel RON 0 0 0 1.6 95 10 0.096 119 0.5toluene 1.504 92 20 Min 0.192 119 Toluene plus 1.408 85-90 (all toluene)other aromatics 100 0.48 100-120 All aromatics 1.12 75-80

Having described the subject matter of the present disclosure in detailand by reference to specific embodiments, it is noted that the variousdetails disclosed in the present disclosure should not be taken to implythat these details relate to elements that are essential components ofthe various described embodiments, even in cases where a particularelement is illustrated in each of the drawings that accompany thepresent description. Further, it will be apparent that modifications andvariations are possible without departing from the scope of the presentdisclosure, including, but not limited to, embodiments defined in theappended claims. More specifically, although some aspects of the presentdisclosure are identified as preferred or particularly advantageous, itis contemplated that the present disclosure is not necessarily limitedto these aspects.

It is noted that one or more of the following claims utilize the term“wherein” as a transitional phrase. For the purposes of definingfeatures discussed in the present disclosure, it is noted that this termis introduced in the claims as an open-ended transitional phrase that isused to introduce a recitation of a series of characteristics of thestructure and should be interpreted in like manner as the more commonlyused open-ended preamble term “comprising.”

It is noted that terms like “preferably”, “generally” and “typically”are not utilized to limit the scope of the claims or to imply thatcertain features are critical, essential, or even important to thedisclosed structures or functions. Rather, these terms are merelyintended to highlight alternative or additional features that may or maynot be utilized in a particular embodiment of the disclosed subjectmatter. Likewise, it is noted that the terms “substantially” and“approximately” and their variants are utilized to represent theinherent degree of uncertainty that may be attributed to anyquantitative comparison, value, measurement or other representation. Assuch, use of these terms represents the degree by which a quantitativerepresentation may vary from a stated reference without resulting in achange in the basic function of the subject matter at issue.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the described embodimentswithout departing from the spirit and scope of the claimed subjectmatter. Thus it is intended that the specification cover themodifications and variations of the various described embodimentsprovided such modification and variations come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A vehicular propulsion system comprising: aninternal combustion engine comprising a combustion chamber; and a fuelsystem configured to provide fuel to the combustion chamber, the fuelsystem comprising: a fuel supply tank configured to contain an onboardsupply of fuel, the fuel supply tank comprising a heat exchangercomprising at least a first compartment for containing the onboard fueland a second compartment disposed within the first compartment; aseparation unit in fluid communication with the fuel supply tank andcomprising at least one adsorbent-based chamber to selectively receiveand separate at least a portion of the onboard supply of fuel into aplurality of components comprising either (a) an octane-rich adsorbateand a cetane-rich remainder or (b) a cetane-rich adsorbate and anoctane-rich remainder; and a product tank in fluid communication withthe separation unit for selectively receiving and containing theremainder, the fuel supply tank and separation unit thermally andfluidly cooperative with one another such that a desorbate produced by aregenerative operation of the separation unit on the octane-rich orcetane-rich adsorbate and that is received by the second compartment inorder to have at least a portion of excess heat that has been impartedto the desorbate is conveyed from the second compartment to an onboardsupply of fuel contained within the first compartment.
 2. The vehicularpropulsion system of claim 1, wherein the fuel system is configured suchthat the onboard supply of fuel is not preheated prior to being conveyedto the separation unit.
 3. The vehicular propulsion system of claim 1,wherein the heat exchanger of the fuel supply tank further comprises athird compartment thermally and fluidly cooperative with the secondcompartment in order to have the third compartment fluidly receive atleast a portion of any remaining portion of the desorbate from thesecond compartment.
 4. The vehicular propulsion system of claim 3,wherein the third compartment is nested within an internal volumedefined by the second compartment.
 5. The vehicular propulsion system ofclaim 3, wherein the third compartment comprises a plurality ofindividual tubes at least some of which are open at both ends.
 6. Thevehicular propulsion system of claim 1, wherein the first and secondcompartments are configured such that the onboard supply of fuel that ispresent in the first compartment and the desorbate that is present inthe second compartment are in fluid communication with one anothersolely through the separation unit.
 7. The vehicular propulsion systemof claim 1, further comprising: a plurality of sensors that areconfigured to acquire at least one operational parameter associated withthe internal combustion engine and the fuel system; and a controllercooperative with the internal combustion engine, sensors and fuel systemand configured to (a) determine an operational condition of the internalcombustion engine based on at least one sensed parameter from at leastone of the plurality of sensors that are associated with the operationof the internal combustion engine, and (b) adjust delivery of at leastone of the onboard fuel, the desorbate and the remainder to thecombustion chamber in response to such determined operational condition.8. The system of claim 1, wherein the at least one adsorbent-basedchamber comprises a plurality of stages such that a first stagepreferentially adsorbs at least one octane-rich compound through the useof an affinity-based adsorbent while the second stage preferentiallyadsorbs at least one cetane-rich compound through the use of asize-selective adsorbent.
 9. A method of providing fuel to an internalcombustion engine, the method comprising: configuring a fuel system tocomprise a fuel supply tank with an onboard fuel being disposed in afirst compartment of the fuel supply tank, a separation unit and aproduct tank cooperative with one another through fuel conduit andresponsive to directions provided by a controller; using the controllerto ascertain an operational condition of the internal combustion engine;and using the controller to either direct the flow of a portion of theonboard fuel to either (a) a combustion chamber of the internalcombustion engine without first passing through the separation unit whenthe engine is in a first operational condition or (b) the separationunit when the engine is in a second operational condition such that anadsorbate in the form of one of an octane-rich fuel component and acetane-rich fuel component collects on a surface of at least one chamberof the separation unit, while a remainder of the portion of the onboardfuel is directed to product tank for storage as the other of thecetane-rich fuel component and the octane-rich fuel component, whereinusing the controller to direct the flow of a portion of the onboard fuelto the separation unit comprises: having the separation unit perform aregenerative operation to create a desorbate from at least a portion ofthe octane-rich or cetane-rich adsorbate; having the desorbate beconveyed from the separation unit to a second compartment that isdisposed within the first compartment of the fuel supply tank; having atleast a portion of the desorbate within the second compartment becondensed by an exchange of heat with the onboard fuel that is presentin the first compartment; and conveying at least one of (a) thedesorbate that is present in the second compartment and (b) theremainder that is in the product tank to the combustion chamber.
 10. Themethod of claim 9, wherein the internal combustion engine is operated ina compression ignition mode.
 11. The method of claim 10, wherein thecompression ignition mode comprises operating as gasoline compressionignition.
 12. The method of claim 9, wherein the internal combustionengine is operated in a spark ignition mode.
 13. The method of claim 9,wherein using the controller to direct the flow of a portion of theonboard fuel to the separation unit comprises further comprisesconveying the desorbate that is present in the second compartment to athird compartment prior to conveying the desorbate to the combustionchamber, the third compartment configured such that it is fluidly andthermally cooperative with the second compartment such that at least aportion of the desorbate within the second compartment that is conveyedto the third compartment is condensed by an exchange of heat between thesecond and third compartments.
 14. The method of claim 9, wherein usingthe controller to ascertain an operational condition of the internalcombustion engine comprises determining an operational condition of theinternal combustion engine based on at least one sensed parameterassociated with the operation thereof.
 15. A fuel system for an internalcombustion engine, the fuel system comprising: a fuel supply tankconfigured to contain an onboard supply of fuel, the fuel supply tankcomprising a heat exchanger comprising at least a first compartment forcontaining the onboard fuel and a second compartment disposed within thefirst compartment; a separation unit in fluid communication with thefuel supply tank and comprising at least one adsorbent-based chamber toselectively receive and separate at least a portion of the onboardsupply of fuel into a plurality of components comprising either (a) anoctane-rich adsorbate and a cetane-rich remainder or (b) a cetane-richadsorbate and an octane-rich remainder; a product tank in fluidcommunication with the separation unit for selectively receiving andcontaining the remainder, the fuel supply tank and separation unitthermally and fluidly cooperative with one another such that a desorbateproduced by a regenerative operation of the separation unit on theoctane-rich or cetane-rich adsorbate and that is received by the secondcompartment in order to have at least a portion of excess heat that hasbeen imparted to the desorbate is conveyed from the second compartmentto an onboard supply of fuel contained within the first compartment; anda controller configured to (a) determine an operational condition of aninternal combustion engine based on at least one sensed parameterassociated with the operation thereof, and (b) adjust delivery of atleast one of the onboard fuel, the desorbate and the remainder to acombustion chamber within the internal combustion engine in response tosuch determined operational condition.
 16. The fuel system of claim 15,wherein the heat exchanger of the fuel supply tank further comprises athird compartment thermally and fluidly cooperative with the secondcompartment in order to have the third compartment fluidly receive atleast a portion of any remaining portion of the desorbate from thesecond compartment.
 17. The fuel system of claim 15, wherein thecontroller being configured to adjust delivery of at least one of theonboard fuel, the desorbate and the remainder to a combustion chamberwithin the internal combustion engine in response to such determinedoperational condition is further configured to adjust at least one of(a) the timing of such delivery to the combustion chamber in response tosuch determined operational condition and (b) the concentration of atleast one of the onboard fuel, desorbate and remainder to the combustionchamber in response to such determined operational condition.